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Immonen et al. (2020). “WPC fines dispersion,” BioResources 15(3), 6561-6575. 6561

Impact of Stone Ground ‘V-fines’ Dispersion and Compatibilization on Polyethylene Wood Plastic Composites

Kirsi Immonen,* Erkki Saharinen, Ilkka Nurminen, Jari Sirviö, and David Sandquist

Recent studies have suggested that blocky mechanical pulp fines (CTMP fines) and fibrillar fines (SMC fines) have a negative impact on biocomposite modulus of rupture (MoR) in compression molded biocomposites. In addition, it was suggested that CTMP fines also have a negative impact on biocomposite modulus of elasticity (MoE). This study investigated whether these findings transfer to other types of cellulose fines material and injection molding. The effect of ‘V-fines’ addition to sawdust- and TMP-based biocomposites was analyzed, with respect to fines concentration, dispersing agent, and compatibilizers. The results indicated that the addition of ‘V-fines’ increased the stiffness (MoE) of all the analyzed compositions, while reducing the elongation at break. The addition of 'V-fines' reduced the tensile and flexural strength of TMP biocomposites, while it was largely unaffected for sawdust biocomposites. Flexural strength for neat 'V-fines' composites showed an increase that was proportional to the remaining pulp fibers composition. The addition of a dispersant agent to the 'V-fines' increased tensile strength, suggesting that an increased dispersion of the 'V-fines' can be achieved and is beneficial to the composite. The effects of the analyzed compatibilizer (polyethyleneoxide) was negligible, except for a small indication of increased MoE for fines / sawdust biocomposites.

Keywords: Composites; Short fiber composites; Wood polymer composites; WPC; Mechanical pulp

manufacturing; Pulp fines; Fines material

Contact information: VTT Technical Research Centre of Finland Ltd, P.O. Box 1000, 02044 VTT, Finland;

*Corresponding author: [email protected]

INTRODUCTION

Recent studies have suggested that blocky mechanical pulp fines (TMP and CTMP

fines) (Peltola et al. 2011a,b, 2014; Miettinen 2016; Sandquist et al. 2020) and fibrillar

fines (SMC fines) (Sandquist et al. 2020) have a negative impact on biocomposite modulus

of rupture (MoR) in compression molded biocomposites. In addition, it was suggested that

CTMP fines also have a negative impact on biocomposite modulus of elasticity (MoE).

The proposed underlying mechanisms include reduced aspect ratio, increased surface area,

and poor dispersion or agglomeration of the fines material. Fines aggregate strongly when

processed under aqueous conditions (Ek 2009). However, for optimal reinforcement

potential in composites, the reinforcing fibers should ideally be well dispersed in the matrix

(Peltola et al. 2014).

In modeling polymer matrix wood fiber composites, fines are often disregarded

(Miettinen 2016; Miettinen et al. 2012, 2015; Newman et al. 2014), as they have limited

or no contribution to reinforcement of strength or stiffness of the composite (Miettinen

2016). Additionally, to achieve reinforcement, the fiber or particle needs to possess a



minimal aspect ratio, which relates to a critical fiber length. Thumm and Dickson (2013)

showed that the critical fiber length for radiata pine pulp reinforcement in biocomposites

is approximately 0.8 mm in length, which results in an approximate aspect ratio of 25

(length/width). Softwood pulp fibers possess a fiber length that is longer (~3 mm)

(Dinwoodie 2000) than the critical fiber length (Thumm and Dickson 2013) prior to

compounding, whereas sawdust and wood flour does not (Stark and Berger 1997b).

Fekete et al. (2018) observed substantial physical reinforcement with low aspect

ratio cellulose fibers in thermoplastic starch, as did Toriz et al. (2002) with lignin particles

in polypropylene (PP). However, in PP, polylactide (PLA), and in polyethylene (PE)

Sandquist et al. (2020), Peltola et al. (2011a, 2014), and Gallagher and McDonald (2013),

respectively, showed negative strength reinforcement of composites with very small wood

particles or fines.

Previous studies on wood flour has indicated that the particle size distribution has

a significant influence on the mechanical properties of wood plastic composites (Stark and

Berger 1997a,b; Stark and Rowlands 2003). Wood flour content up to 40% by weight

yielded an increase in physical properties, after which properties start to plateau (Stark and

Berger 1997a). Smaller diameter wood flour particles gave an higher increase in strength,

elongation, and stiffness compared to larger particles (Stark and Berger 1997b), especially

comparing 60 µm with 500 µm fractions.

In sawdust-based wood-plastic composites (WPC), Islam and Islam (2011) showed

that cetyltrimethylammonium bromide (CTAB)-modified SD improved almost all

mechanical properties of PE-based biocomposites in the range of 20 to 35 wt% SD. This

result indicates that there is significant room for improved compatibilization between SD

and PE. Similarly, Godard et al. (2009) showed a significant increase in both strength and

stiffness with the addition of MA-PE compatibilization agent to 40 wt% containing SD /

PE composites. The highest effect was seen for fine SD particles (length average 0.57 mm),

but also significant for intermediate (1.48 mm) and coarse SD particles (1.78 mm). Hillig

et al. (2008) reported similar findings.

Viksne et al. (2004) analyzed the impact of a paraffin and a maleic anhydride (MA)

containing modification on SD/PE composite. The paraffin modification significantly

improved dispersion, with a subsequent improvement in the strength of the composite.

Oppositely, the MA containing modifier improved the stiffness, but less prominently the

strength, which corresponds to an increase in compatibilization.

The aims of this study were to investigate the effect of fines material addition to

SD- and TMP-based biocomposites and to study what effect the addition of a dispersing

agent and a compatibilizer may have on fines material in the SD ad TMP composites. The

selected dispersion agent Arosurf PA 780V is a commercially blend of ionic and non-ionic

surfactants used in tissue paper production. The selected compatibilization agent was

polyethyleneoxide (POE). Lu et al. (2005) showed that POE is a less effective

compatibilizer than a MA-PE based option. However, POE was selected because it is not

chemically reactive, and it was feared that premature reactivity would limit dispersion and

obscure the interpretation of the results. Other advantages of POE are that it is a

thermoplastic, water soluble additive, easy to apply on cellulose fibre surface to provide

improved fibre dispersion, and it is compatible with several thermoplastic polymers.



EXPERIMENTAL

Materials and Methods

Saw dust

The utilized wood sawdust (SD) was from a commercial lumber production facility

(local sawmill, Southern Finland), and was predominantly made up of short shives (bundles

of fibers) from Scots pine (Pinus sylvestris), with an average particle size of 450 µm and

presented in Fig. 1. The fines material concentration of material that passed through a 200-

mesh sieve was negligible.

Thermomechanical pulp

Commercial thermomechanical pulp (TMP) produced from spruce (Picea abies)

from a Finish producer was utilized in the trial. The fines material content was stated by

the suppler to be approximately 20% by weight.

Grinding stone preparation

The grinding stone for the custom laboratory grinder was a Norton A601 (Saint-

Gobain Abrasives Canada Inc, Hamilton, Ontario, Canada) with a diameter of 300 mm,

and was first milled flat, removing the original stone pattern. On the flat surface, a new

profile was milled with 15⁰-angle chamfers as shown in Fig. 1.

Fig. 1. Dimensions of angles (the axis are not at the same scale in the figure) Separator.

Production of V-fines

Production of V-fines was made according to process described in Nurminen et al.

(2018). The wood raw material used was never dried Spruce (Picea abies). Dry matter

content of the wood was on average 44.8%. Wood logs were cut to blocks for grinding.

Care was taken to utilize wood materials that was as similar as possible in appearance.

The previously described custom-built laboratory grinder (Nurminen et al. 2018)

used a grinding area of 35 mm in both length and in width. Peripheral speed of the stone

was 20 m/s. The shower water temperature varied from 60 °C to 70 °C, and the wood

feeding rate was 0.5 mm/s. The pulp was screened through 4 mm hole sieve to remove

larger, unground particles.

The fines concentration after grinding was low, approximately 1.2%. To increase

the concentration, the suspension was concentrated via a WESTFALIA TSC 6-01-576

(GEA Westfalia Separator GmbH, Oelde, Germany) separator. The rotation speed was

12000 rpm; the outlet interval was 100 to 540 s and was increased while the consistency

decreased. The feeding was 300 L/h, and the water phase was returned to feeding container.



The original dry mater content of the V-fines suspension was 1.2%, the total volume

of fines suspension processed for concentration was approximately 700 L, with a final dry

matter content of the V-fines slurry of 4.5 to 5.3%.

V-fine treatment with debonder agent

The commercial debonder Arosurf PA 780V (Evonik Industries, Essen, Germany)

was used as received and according to the manufacturer’s instructions. Arosurf PA 780V

was diluted with water, added into the concentrated V-fines slurry (consistency 2.5 to 3%),

and stirred for 1 h at room temperature followed by spray drying. The debonder content

after mixing was 1% by weight of the slurry. The Arosurf PA 780V debonder is a

commercial fluff pulp debonder consisting of a blend of non-ionic and cationic compounds.

V-fine treatment with compatibilization agent

The non-chemically reactive compatibilizer polyethyleneoxide (PEO) (Polyox™

WSR N750, DOW Chemical Company, Texas City, USA) was mixed into water with

Ystral disperser (Ystral GmbH, Ballrechten-Dottingen, Germany) and then mixed with the

V-fines slurry, followed by spray drying. The amount of PEO was 17% of the weight of

dry fines. It was assumed that a high amount of PEO in slurry will cover fines particles at

least partially during drying and at the high temperature in extruder PEO melts and particles

separates from aggregates at high shear of extruder.

Spray drying of V-fines and modified V-fines

Spray-drying of V-fines was performed at VTT Rajamäki with NIRO Spray Dryer

P-6.3 (GEA NIRO A/S, Soeborg, Denmark). The fines slurry was fed on the atomizer at

the consistency of 2.5% to 3%. The temperature of the coming airflow was 200 °C, which

increased the temperature of the product to 85 to 90 °C. Feeding speed of slurry was 25.8

kg/h. The energy consumption was very high, 49.8 MWh/t, due to the large amount of

water being vaporize.

The final product was a yellowish free-flowing flour (Fig. 2). The larger particles

in Fig. 2 were weak agglomerates that formed when the flour was exposed to air moisture.

When kept under dry conditions, these agglomerates were not present.

Fig. 2. Fines after spray-drying



Mixing of V-fines with sawdust or TMP

Both virgin and modified V-fines were dry-blended with SD and TMP via bag

mixing 5 min prior to compounding.

Polymer matrix

The polymer used for the preparation of all the composite materials were Braskems

bio-based polyethylene HDPE SHA7260 (Braskem, São Paulo, Brazil). This polymer is

derived from sugar cane saccharose.

Composite compounding

The compounding of materials to total fibre content 40% in PE were made using

co-rotating Berstorff ZE 25x33D compounder (Besrtorff GmbH, Hanover, Germany) and

injection moulded to standard (ISO 527-2 2012) dog bone shaped test pieces with Engel

ES 200/50 HL (Engel Maschinenbau GmbH, Schwefberg, Austria) injection moulding

machine.

Mechanical testing

Tensile testing was performed according to ISO 527 and flexural test according to

ISO 178 (2019) using Instron 4505 mechanical test equipment (Instron Corp., Canton, MA,

USA). Samples were dog bone-shaped standard samples (ISO 527-2 (2012)), and the

results were an average of minimum five replicates.

Charpy impact strength was tested according to ISO 179-2 (1997) using unnotched

samples flatwise and a Charpy Ceast Resil 5.5 Impact Strength Machine (CEAST S.p.a.

Torino, Italy). The sample size was 4 mm x 10 mm x 100 mm, and the average of 10

samples was utilized for further analysis. All the tested samples were conditioned in 23 °C

and 50% relative moisture for minimum five days before testing.

Microscopic imaging for composites

The morphology of fibres and injection-moulded samples was studied by scanning

electron microscopy (SEM). The sample surface was coated with gold particles. In

injection moulded samples the scanning was made on cross-cut surfaces. Samples were

observed on a Jeol JSM T100 with a voltage of 25 kV (Tokyo, Japan).

Microscopic imaging of V-fines

Liquid samples were suspended in water in order to improve the visibility of sample

details by diluting. Samples were spread on a microscopy slide and covered with a cover

slip. Samples were imaged using confocal laser scanning microscopy (CLSM) equipment

consisting of a Zeiss LSM 710 attached to an Axio Imager Z microscope (Zeiss, Jena,

Germany).

Each sample view was imaged without staining with transmission mode and

utilising the autofluorescence properties of the sample structures. For the latter, a diode

laser line of 405 nm was used for excitation, and emission was collected at 424 to 540 nm.

Images were assembled of the optical sections taken using 10x, 20x and 40x objectives

(Zeiss EC Epiplan-Neofluar, Cambridge, UK) and ZEN software (Zeiss, Jena, Germany).



RESULTS AND DISCUSSION

Particle Size Estimate of V-fines With a grinding stone profile of angle of 15°, the amount of material that did not

pass through a 200 mesh was initially 5%, but it increased and stabilized at 9%.

Fig. 3. CLSM microscopy autofluorescence image of V-fines particles, to show the dispersion of the fines material in the matrix. The matrix is dark as it does not possess autofluorescence.

Fig. 4. SEM-pictures of injection molded PE-40% fibre composites fracture surfaces, 100x enlargedt. A) TMP, B) V-fine wood ref., C) Arosurf 780V mod. V-fines, D) PEO modified V-fines



The materials from both runs was mixed, and in the final mixture the amount of

material that did not pass through a 200-mesh size was approximately 7%. A representative

overview of the fines structures are shown in Fig. 3.

Dispersion and compatibilization of the cellulose material in the composite matrix

Wood material, fibers, and composite samples were examined with SEM to

estimate the dispersion of the cellulose material and to investigate the interface between

cellulose and matrix. As shown in Fig. 5A-D, the cellulose materials of TMP and V-fines

were well dispersed in the matrix, with no apparent agglomeration. In the V-fines samples,

some fibers were still present (approximately 7 wt%), as apparent in Fig. 4B-D.

Peltola et al. (2014, 2019) showed that for PP and PLA in particular, the

compatibility between matrix and TMP is high. They postulated that this is related to the

surface lignin on these fibers and the interaction with the OH-groups in the polymer matrix.

However, PE lacks OH-functionality and is significantly more hydrophobic than PP or

PLA.

As shown in Fig. 5A-B, uncompatibilized TMP and V-fines showed comparatively

less strong interfacial bonding (arrows) compared with the compatibilized V-fines in Fig.

5C-D. This supports the earlier reports of improved compatibilization of PEO with

cellulose and a PE matrix (Lu et al. 2005).

Fig. 5. SEM-pictures of injection moulded PE-40% fibre composites fracture surfaces with 7500x enlargement. A) TMP, B) V-fines, C) Arosurf 780V modified V-fines, D) PEO modified V-fines



Comparison of TMP, SD and V-fines composites

Figures 6 through 8 summarize the mechanical testing results of all the composite

combinations. Overall, there was a large agreement between the tensional (Fig. 6) and

flexural (Fig. 7) results.

Focusing on the TMP, SD, and V-fines results without any dispersing agent or

compatibilizer, several interesting inferences can be drawn. Firstly, the addition of

uncompatibilized SD to the HD-PE matrix increased the tensile and flexural strength and

stiffness, while reducing impact strength, in agreement to earlier reports (Hillig et al. 2008;

Godard et al. 2009; Islam and Islam 2011). The addition of TMP to the HD-PE increased

the mechanical properties of the composite material, also in agreement with earlier reports

(Mertens et al. 2017). The addition of V-fines also increased both the strength and stiffness

of the composite compared to neat PE. It needs to be reiterated that the V-fines contained

approximately 7 wt% material that does not pass through a 200 mesh and is mainly made

up of fibers.

As a simplified hypothesis, assuming 80 wt% fiber content of the TMP pulp as

stated by the producer; the tensile strength of a 100 wt-% TMP fiber composite was

estimated at (28.4/0.8) = 35.5 MPa. The recorded tensile strength of the pure matrix was

12.3 MPa. Utilizing a linear regression, a composite containing 7 wt% fibers would be

estimated to show a strength of (12.3 + (35.5-12.3) * 0.07) = 13.92 MPa. This shows a

strong agreement with the recorded tensile strength of the fines reference composite at

13.90 MPa.

Fig. 6. Summary of tensile tests results for reference PE, 40/60 fines/PE, 40/60 TMP/PE and 40/60 SD/PE composites. Fines refers to V-fines, and was consistently added at a 5% concentration, independent of modification, to the TMP and SD composites. Abbreviations: Compat. Refers to the POE Compatibilizer Polyox WSR N750; Debonder refers to the Arosurf PA 780V debonder.

Te

ns

ile

Str

en

gth

(M

Pa

)

Te

ns

ile

Mo

du

lus (

GP

a)



Fig. 7. Summary of flexural tests results for reference PE, 40/60 fines/PE, 40/60 TMP/PE and 40/60 SD/PE composites. Fines refers to V-fines, and was consistently added at a 5% concentration, independent of modification, to the TMP and SD composites. Abbreviations: Compat. Refers to the POE Compatibilizer Polyox WSR N750; Debonder refers to the Arosurf PA 780V debonder.

Fig. 8. Summary of Charpy impact strength tests results for reference PE, 40/60 V-fines/PE, 40/60 TMP/PE and 40/60 SD/PE composites. Fines refers to V-fines, and was consistently added at a 5% concentration, independent of modification, to the TMP and SD composites. Abbreviations: Compat. Refers to the POE Compatibilizer Polyox WSR N750; Debonder refers to the Arosurf PA 780V debonder.

Fle

xu

ral S

tre

ng

th (

MP

a)

Fle

xu

ral M

od

ulu

s (

GP

a)

Imp

ac

t S

tren

gth

(k

J/m

2)



Effect of dispersant agent or compatibilizer to V-fines

The addition of a dispersing agent and compatibilization agent had only moderate

effects on the mechanical properties of the composite material. Of note, in both tension and

flexural properties there was a small increase in strength, which supports the postulation

that the surfactant dispersion agent increases the dispersion of the fines material in the

matrix. This is supported by a small, but not statistically significant, increase in impact

strength.

Secondly, the addition of PEO compatibilization agent resulted in a small drop in

stiffness for both tensional and flexural mechanical properties. A similar decrease was

observed in impact strength. This points either towards an increased agglomeration of the

fines material, or alternatively an overall reduced interfacial strength. This result is

unexpected and counter-intuitive, as the PEO is a non-reactive compatibilization agent.

Until a more complete analysis can be performed, this result was attributed to an increase

in agglomeration of the fines prior to compounding.

Effect of addition of V-fines to TMP and SD composites

Focusing first on the unmodified V-fines, there was a clear effect in both TMP and

SD composites in both tensile and flexural properties. For the TMP-based composites,

there was a drop in strength, which was not recovered through any of the modifications.

This drop was larger than what would be expected from a rule of mixture decrease of fibres.

Simultaneously, there was a large increase in tensional stiffness (elastic modulus), which

was not seen in the flexural results. There was a corresponding reduction in impact

strength. Flexural testing of materials is a combination of a material’s basic tensile,

compressive, and shear properties. The interpretation of these results is that the

introduction of the fines materials affects the shear and compression properties, alongside

an overall reduction in strength and stiffness. The authors have not found any explanation

for this behaviour, and postulate that a potential mechanism could be that the fines are

agglomerating on the fiber surfaces, creating a ‘slip layer’. The recorded increased increase

in tensional stiffness may be due to increased surface area in total exposed to the polymer

matrix.

For the SD-based composites, the effect was less dramatic than for the TMP

composites. As there was less strength reinforcement from the SD particles, no real loss

was recorded with the addition of V-fines. There was an indication of similar loss of

strength and impact resistance as recorded for the TMP composites. Similarly, this result

was interpreted as the increase in tensile stiffness for an increase in total surface area with

the addition of V-fines, which is supported by the recorded increase in tensional stiffness.

CONCLUSIONS

1. The addition of a dispersant agent to V-fines increased mechanical properties of the

wood-polyethylene composites, indicating that a better dispersion can be achieved.

2. Polyethyleneoxide (POE) provided little or no compatibilization at the analysed levels

in a polyethylene-based wood plastic composite.

3. The addition of V-fines to a thermomechanical pulp (TMP)-based wood plastic

composite reduced all mechanical properties apart from tensional stiffness. This result

may be related to an increase in cellulose surface area.



4. Similarly, the addition of V-fines to a saw dust (SD)-based wood plastic composite

reduced most mechanical properties, while increasing tensional stiffness. This effect

may be related to an increase in cellulose surface area.

ACKNOWLEDGMENTS

The authors thank Upi Anttila and Mirja Nygård for performing the processing and

characterization work. The authors are grateful for the support of the Finish national

research grant to VTT for supporting this work.

REFERENCES CITED

Dinwoodie, J. M. (2000). Timber: Its Nature and Behaviour, CRC Press, Boca Raton,

FL, USA.

Ek, M. (2009). Paper Chemistry and Technology, De Gruyter, Berlin.

Fekete, E., Kun, D., and Móczó, J. (2018). “Thermoplastic starch/wood composites:

effect of processing technology, interfacial interactions and particle characteristics,”

Periodica Polytechnica Chemical Engineering 62(2), 129-136. DOI:

10.3311/PPch.11228

Gallagher, L. W., and McDonald, A. G. (2013). “The effect of micron sized wood fibers

in wood plastic composites,” Maderas. Ciencia y tecnología 15(3), 357-374. DOI:

10.4067/S0718-221X2013005000028

Godard, F., Vincent, M., Agassant, J.-F., and Vergnes, B. (2009). “Rheological behavior

and mechanical properties of sawdust/polyethylene composites,” Journal of Applied

Polymer Science 112(4), 2559-2566. DOI: 10.1002/app.29847

Hillig, É., Freire, E., Zattera, A. J., Zanoto, G., Grison, K., and Zeni, M. (2008). “Use of

sawdust in polyethylene composites,” Progress in Rubber, Plastics and Recycling

Technology 24(2), 113-119. DOI: 10.1177/147776060802400202

Islam, Md. N., and Islam, Md. S. (2011). “Mechanical properties of chemically treated

sawdust-reinforced recycled polyethylene composites,” Industrial & Engineering

Chemistry Research 50(19), 11124-11129. DOI: 10.1021/ie201077k

ISO 178 (2019). “Plastics — Determination of flexural properties,” International

Organization for Standardization, Geneva, Switzerland

ISO 179-2 (1997). “Plastics — Determination of Charpy impact properties — Part 2:

Instrumented impact test,” International Organization for Standardization, Geneva,

Switzerland

ISO 527-2 (2012). "Plastics — Determination of tensile properties — Part 2: Test

conditions for moulding and extrusion plastics," International Organization for

Standardization, Geneva, Switzerland.

Lu, J. Z., Wu, Q., and Negulescu, I. I. (2005). “Wood-fiber/high-density-polyethylene

composites: Coupling agent performance,” Journal of Applied Polymer Science

96(1), 93-102.

Mertens, O., Gurr, J., and Krause, A. (2017). “The utilization of thermomechanical pulp

fibers in WPC: A review,” Journal of Applied Polymer Science 134(31), 45161. DOI:

10.1002/app.45161



Miettinen, A. (2016). Characterization of Three-dimensional Microstructure of

Composite Materials by X-ray Tomography (Research Report), Department of

Physics, University of Jyväskylä, Jyväskylä, Finland.

Miettinen, A., Luengo Hendriks, C. L., Chinga-Carrasco, G., Gamstedt, E. K., and

Kataja, M. (2012). “A non-destructive X-ray microtomography approach for

measuring fibre length in short-fibre composites,” Composites Science and

Technology 72(15), 1901-1908. DOI: 10.1016/j.compscitech.2012.08.008

Miettinen, A., Ojala, A., Wikström, L., Joffe, R., Madsen, B., Nättinen, K., and Kataja,

M. (2015). “Non-destructive automatic determination of aspect ratio and cross-

sectional properties of fibres,” Composites Part A: Applied Science and

Manufacturing 77, 188-194.

Newman, R. H., Hebert, P., Dickson, A. R., Even, D., Fernyhough, A., and Sandquist, D.

(2014). “Micromechanical modelling for wood-fibre reinforced plastics in which the

fibres are neither stiff nor rod-like,” Composites Part A: Applied Science and

Manufacturing 65, 57-63. DOI: 10.1016/j.compositesa.2014.05.012

Nurminen, I., Saharinen, E., and Sirviö, J. (2018). “New technology for producing

fibrillar fines directly from wood,” BioResources 13(3), 5032-5041. DOI:

10.15376/biores.13.3.5032-5041

Peltola, H., Immonen, K., Johansson, L.-S., Virkajärvi, J., and Sandquist, D. (2019).

“Influence of pulp bleaching and compatibilizer selection on performance of pulp

fiber reinforced PLA biocomposites,” Journal of Applied Polymer Science 136(37),

47955-47967. DOI: https://doi.org/10.1002/app.47955

Peltola, H., Laatikainen, E., and Jetsu, P. (2011a). “Effects of physical treatment of wood

fibres on fibre morphology and biocomposite properties,” Plastics, Rubber and

Composites 40(2), 86-92. DOI: 10.1179/174328911X12988622801016

Peltola, H., Madsen, B., Joffe, R., and Nättinen, K. (2011b). “Experimental study of fiber

length and orientation in injection molded natural fiber/starch acetate composites,”

Advances in Materials Science and Engineering 2011, 1-7. DOI:

10.1155/2011/891940

Peltola, H., Pääkkönen, E., Jetsu, P., and Heinemann, S. (2014). “Wood based PLA and

PP composites: Effect of fibre type and matrix polymer on fibre morphology,

dispersion and composite properties,” Composites Part A: Applied Science and

Manufacturing 61, 13-22. DOI: 10.1016/j.compositesa.2014.02.002

Sandquist, D., Thumm, A., and Dickson, A. R. (2020). “The influence of fines material

on the mechanical performance of wood fiber polypropylene composites,”

BioResources 15(1), 457-468. DOI: 10.15376/biores.15.1.457-468

Stark, N., and Berger, M. (1997a). “Effect of species and particle size on properties of

wood-flour-filled polypropylene composites,” in: Proceeding of Functional Fillers

for Thermoplastic and Thermosets, San Diego, USA, 8-10.

Stark, N. M., and Berger, M. J. (1997b). “Effect of particle size on properties of wood-

flour reinforced polypropylene composites,” in: Proceedings of the Fourth

International Conference on Woodfibre-Plastic Composites, Madison, USA, 12-14.

Stark, N. M., and Rowlands, R. E. (2003). “Effects of wood fiber characteristics on

mechanical properties of wood/polypropylene composites,” Wood and Fiber Science

35, 8.

Thumm, A., and Dickson, A. R. (2013). “The influence of fibre length and damage on the

mechanical performance of polypropylene/wood pulp composites,” Composites Part



A: Applied Science and Manufacturing 46, 45-52. DOI:

10.1016/j.compositesa.2012.10.009

Toriz, G., Denes, F., and Young, R. A. (2002). “Lignin-polypropylene composites. Part

1: Composites from unmodified lignin and polypropylene,” Polymer Composites

23(5), 806-813. DOI: 10.1002/pc.10478

Viksne, A., Rence, L., and Berzina, R. (2004). “Influence of modifiers on the

physicomechanical properties of sawdust-polyethylene composites,” Mechanics of

Composite Materials 40(2), 169-178. DOI: 10.1023/B:MOCM.0000025491.90614.52

Article submitted: February 5, 2020; Peer review completed: April 3, 2020; Revised

version received and accepted: July 4, 2020; Published: July 8, 2020.

DOI: 10.15376/biores.15.3.6561-6575



Appendix

Table S1. Tensile Strength Results for Injection Moulded PE Composites with Total Fibre Content of 40%

Sample Tensile strength

at yield Tensile strength

at break Modulus (Auto

Young) Elongation at

break

MPa s.d. MPa s.d. MPa s.d. % s.d.

Bio-PE 18.9 0.2 12.3 0.7 1033 325 103 85

PE-Fines ref. 13.9 0.1 13.1 0.2 2084 96 3.4 0.2

PE-Fines DA1 15.2 0.1 14.8 0.1 2143 107 3.3 0.2

PE-Fines PEO 14.7 0 14.3 0.1 1869 70 3.1 0.5

PE-TMP 28.6 0.4 28.4 0.3 3446 193 1.7 0.1

PE-TMP-Fines ref. 22.6 0.3 22.4 0.3 3957 110 1.5 0.1

PE-TMP-Fines DA1 22.4 0.2 22.3 0.2 4086 210 1.5 0.1

PE-TMP-Fines PEO 22.9 0.3 22.8 0.3 4008 136 1.5 0.1

PE-SD ref. 15.4 0.2 15.4 0.2 2525 545 2 0.2

PE-SD-Fines ref. 16 0.1 15.3 0.3 3130 183 2.2 0.2

PE-SD-Fines DA1 15.6 0 14.9 0.4 3210 189 2.2 0.2

PE-SD-Fines PEO 15.2 0.1 14.4 0.2 3482 297 2 0.2

Table S2. Flexural Strength Results for Injection Moulded PE Composites with Total Fibre Content of 40%

Sample Flexural strength

at yield Modulus

(Auto Young) Elongation

Flexural load at yield

MPa s.d. MPa s.d. % s.d. N s.d.

Bio-PE 21.7 0.1 855 11 6.2 0.1 36.6 0.1

PE-Fines ref. 26.4 0.4 2041 39 4 0.2 44.6 0.2

PE-Fines DA1 29 0.4 2111 49 4 0.1 48.2 0.1

PE-Fines PEO 27.1 0.2 1825 32 4.1 0.1 45.7 0.2

PE-TMP 46.9 0.8 3512 115 2.6 0.1 76.5 0.6

PE-TMP-Fines ref. 38.5 0.6 3269 34 2.5 0.1 66.3 0.9

PE-TMP-Fines DA1 38.7 0.2 3416 52 2.4 0.1 66.4 0.5

PE-TMP-Fines PEO 39 0.3 3354 16 2.6 0.1 67.1 0.7

PE-SD ref. 29.5 0.5 2729 84 3.3 0.2 53.4 0.9

PE-SD-Fines ref. 29.3 0.2 2501 64 3.9 0.1 51.1 0.3

PE-SD-Fines DA1 29.5 0.4 2782 10 3.6 0.2 51.6 0.6

PE-SD-Fines PEO 28.8 0.5 2854 40 3.3 0.1 49 0.8



Table S3. Charpy Impact Strength (Unnotched) Results for Injection Moulded PE Composites with Total Fibre Content of 40%

Charpy impact strength

Sample kJ/m2 s.d.

Bio-PE 118 15

PE-Fines ref. 6.3 0.3

PE-Fines DA1 7.1 0.6

PE-Fines PEO 6.1 0.6

PE-TMP 7.1 0.4

PE-TMP-Fines ref. 6.1 0.85

PE-TMP-Fines DA1 6 0.58

PE-TMP-Fines PEO 6.5 0.69

PE-SD ref. 5.3 0.69

PE-SD-Fines ref. 4.8 0.6

PE-SD-Fines DA1 4.9 0.74

PE-SD-Fines PEO 4.8 0.65

PEER-REVIEWED ARTICLE bioresources€¦ · Spray-drying of V-fines was performed at VTT Rajamäki...

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Transcript of PEER-REVIEWED ARTICLE bioresources€¦ · Spray-drying of V-fines was performed at VTT Rajamäki...